Question

Which of the following statement is true regarding body is in equilibrium?
1. Body must be in translational equilibrium
2. Body must be in rotational equilibrium
3. Either 1 or 2
4. Both 1 and 2

Answer 1

Correct Answer - Option 4 : Both 1 and 2

CONCEPT:

• Equilibrium: It is a state of a body in which overall change in a body is zero.
• Translational Equilibrium: A body is said to be in translational equilibrium if the net sum of all the forces (F) acting on a body is zero.

Σ F = 0

F_net = 0

F₁ + F₂ + F₃+ ............... + F_n = 0

• Rotational Equilibrium: A body is said to be in rotational equilibrium if the net sum of all the torque (τ) acting on a body is zero.

Σ τ = 0

τ_net = 0 

τ₁ +τ₂ + τ₃ + .................. + τ_n = 0

EXPLANATION:

• A body is said to be in equilibrium if it is in translational equilibrium and rotational equilibrium.
• Both translational and rotational equilibrium is required to a body in equilibrium.

Hence option 4 is correct.
 

• Solving the numerical problem on the equilibrium of forces always draws the FBD (Fee Body Diagram). 
• A simplified version of the body on which all external forces are shown is called FBD (Fee Body Diagram) of the given body.